USDA, Agricultural Research Service, Egg Safety and Quality Research Unit, Athens, GA 30605, USA.
Poult Sci. 2010 Aug;89(8):1732-6. doi: 10.3382/ps.2009-00440.
Although deposition of Salmonella Enteritidis inside yolks is less common than deposition in albumen or on the vitelline (yolk) membrane in naturally contaminated eggs laid by infected hens, bacterial migration into the yolk to reach its nutrient-rich contents could lead to extensive multiplication. The present study used an in vitro egg contamination model to assess the ability of small initial numbers of Salmonella Enteritidis to penetrate the vitelline membrane and multiply inside yolks of eggs laid by 6 genetically distinct commercial lines of hens during 24 h of storage at 30 degrees C. Eggs from each line were tested at 4 different hen ages by inoculation of approximately 100 cfu of Salmonella Enteritidis onto the outside of the vitelline membranes of intact yolks in plastic centrifuge tubes and then adding back the albumen into each tube before incubation. Overall, the frequency of penetration of Salmonella Enteritidis into the yolk contents of eggs from individual lines of hens ranged from 30 to 58% and the mean concentration of Salmonella Enteritidis in yolk contents after incubation ranged from 0.8 to 2.0 log(10) cfu/mL. For both of these parameters, values for one hen line were significantly higher than for 2 other lines, but no other differences were observed. Hen age did not have a significant effect on egg yolk penetration by Salmonella Enteritidis. These results indicate that opportunities for the migration and growth of small initial numbers of Salmonella Enteritidis to attain more dangerous levels inside contaminated eggs during storage at warm temperatures can sometimes vary between different lines of laying hens.
虽然与受感染母鸡所产自然污染鸡蛋的蛋清或卵黄膜(蛋黄)相比,肠炎沙门氏菌在蛋黄内的沉积较为少见,但细菌迁移至蛋黄以获取其富含营养的内容物可导致大量繁殖。本研究采用体外鸡蛋污染模型,评估少量初始肠炎沙门氏菌穿透卵黄膜并在 30°C 储存 24 小时期间在母鸡产的蛋黄内繁殖的能力。对来自 6 种不同商业母鸡品系的鸡蛋进行了研究,在 4 个不同母鸡年龄下,通过在塑料离心管中完整蛋黄的卵黄膜外接种约 100 cfu 的肠炎沙门氏菌,随后向每个管中添加蛋清,然后进行孵育。总体而言,肠炎沙门氏菌穿透母鸡各品系鸡蛋蛋黄内容物的频率为 30%至 58%,孵育后蛋黄内容物中肠炎沙门氏菌的平均浓度为 0.8 至 2.0 log(10) cfu/mL。对于这两个参数,一个母鸡品系的值明显高于另外 2 个品系,但未观察到其他差异。母鸡年龄对肠炎沙门氏菌穿透鸡蛋蛋黄没有显著影响。这些结果表明,在温暖温度下储存期间,污染鸡蛋内少量初始肠炎沙门氏菌的迁移和生长达到更危险水平的机会有时在不同的母鸡品系之间会有所不同。